GB2196466A

GB2196466A - Tape guide for videotape cassette

Info

Publication number: GB2196466A
Application number: GB08722313A
Authority: GB
Inventors: Vincent Peter Teuber
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1986-10-14
Filing date: 1987-09-22
Publication date: 1988-04-27
Also published as: GB8722313D0; JPS6362987U; DE8713607U1

Abstract

A tape guide 24 (also Figs. 2 and 6) for a videotape cassette is formed as an arcuate segment of a cylinder to increase the radius of the tape guide without substantially increasing the area occupied by the tape guide within the cassette. In an alternative embodiment (Figs. 3 and 7) two tape guides 26,43 are provided, guide 43 partially redirecting the tape path when reel 16 is nearly fully wound (Fig. 7). Upper surfaces of keyed support (34) (Fig. 2) and studs (46) (Fig. 3) may be rounded or bevelled to facilitate assembly. <IMAGE>

Description

SPECIFICATION Tape guide for videotape cassette Technical Field The present invention relates to videotape cassettes, and particularly, tape guides used therein for redirecting the direction of tape travel within the cassette.

Background Art A substantially typical videotape cartridge, generally denoted as 10, is illustrated in Fig. 1 and comprises a rectangular, box-shaped housing 12 which encloses two reels 14 and 16 upon which is helically wound opposite ends of a recording tape 18. The recording tape 18 is directed along the front surface 20 of the housing 12 by tape guides located adjacent this front surface 20 of the housing 12.

Tape guides used in the prior art are illustrated by Figs. 4 and 5 and consist of tubular cylinders or pins 22. By using a guide 22 which is completely cylindrical, the radius of the guides 22 is limited by the area available within the housing 12 to a relatively small radius of approximately 2.5 mm. Prolonged contact of the tape 18 with a structure of such a small radius causes the tape 18 to acquire a "cold set" or permanent deformation which results in signal distortion. This problem has long been recognized and it has been known that a larger radius is desirable. Unfortunately, as stated, the radius of the guides 22 is limited by the space available within the housing 12.

Disclosure of Invention The present invention has achieved a substantial increase in the radius of the tape guides used to redirect the tape path without substantially increasing the area occupied by the tape guides within the cassette by providing a tape guide including an arcuate segment of a cylinder disposed perpendicular to the direction of tape travel, the arcuate segment including that portion of a cylinder which contacts the tape with the remaining arcuate portion of the cylinder being eliminated from the tape guide to reduce the area occupied within the tape cassette. The tape guide of the present invention preferably comprises a 1800 segment of a cylinder and may include flanges extending from the arcuate segment to contain the tape in contact with the tape guide.

Brief Description of the Drawings The present invention will be more fully described with reference to the accompanying drawings, wherein like numbers refer to like parts in the several views, and wherein: Figure 1 is a top view of a videotape cassette with a portion broken away to illustrate interior details; Figure 2 is a perspective view of a first embodiment of a tape guide according to the present invention and a perspective view of a portion of the videotape cassette; Figure 3 is a perspective view of a second embodiment of a tape guide according to the present invention and a perspective view of a portion of the videotape cassette; Figure 4 and Figure 5 are sectional views of tape guides according to the prior art and plan views of portions of videotape cassettes;; Figure 6 is a cross-sectional, plan view of the first embodiment of the tape guide according to the present invention and a plan view of a portion of the videotape cassette; and Figure 7 is a cross-sectional, plan view of the second embodiment of the tape guide according to the present invention and a plan view of a portion of the videotape cassette.

Detailed Description Fig. 1 illustrates a videotape cassette, generally indicated as 10, which includes a rectangular, box-like housing 12 which encloses two tape reels 14 and 16 upon which is convolutely wound opposite ends of a magnetic recording tape 18. Between- the two reels 14 and 16, the recording tape 18 is guided along the front surface 20 of the housing 12 by tape guides 24 and 26 which are the subject of the present invention. Figs. 2, 3, 6 and 7 illustrate the tape guides 24 and 26 of the present invention in greater detail, and Figs. 4 and 5 illustrate conventional tape guides 22 which are either tubular cylinders or solid pins.

The first embodiment of the tape guide 24 according to the present invention is illustrated by Figs. 2 and 6 and is comprised of an arcuate segment 28 of a cylinder which encompasses substantially 1800 of a complete cylinder. The tape guide 24 includes a longitudinal bore having an enlarged cross-sectional dimensions 32 which is adapted to accept a keyed support 34 molded as a part of the housing 12. The support 34 is keyed to prevent rotation of the tape guide 24. The tape guide 24 further includes end flanges 36 which extend perpendicularly from the cylindrical surface of the arcuate segment 28 of the tape guide 24 to retain the recording tape 18 therebetween and maintain the tape 18 in contact with the arcuate segment 28.

As illustrated by Figs. 3 and 7, the second embodiment of the tape guide 26 also includes an arcuate segment 38 of a cylinder which also preferably encompasses substantially 180 of a complete cylinder. The arcuate segment 38 is supported by a small cylinder 40 molded in attachment with the arcuate segment 38 and the support cylinder 40 and arcuate segment 38 are molded as a part of a base plate 42 which supports a second tape guide 43 adjacent and substantially identical to the first guide 26. The support cylinders 40 and the base plate 42 are molded with two cylindrical bores 44 which are adapted to accept two cylindrical studs 46 molded as a part of the housing 12.The studs 46 need not be keyed as is the support 34 of Fig. 2 since rotation of the tape guide 26 is prevented by the fact of their being two studs 46 rather than the single support 34 associated with the tape guide 24.

As shown in Fig. 7, the second tape guide 43 of the pair is necessary to partially redirect the path of the tape 18 when the reel 16 is nearly fully wound. The path of the tape taken in this situation is illustrated by the phantom line 48 of Figs. 5 and 7.

The reason for providing tape guides 24 and 26 comprised of the arcuate segments 28 and 38 is that such a construction allows the radius of curvature of the portion of the tape guide 24 or 26 in contact with the tape 18 to be substantially increased over the radius of curvature presented by the conventional tape guides 22 shown in Figs. 4 and 5 without substantially increasing the area occupied by the tape guides within the housing 12. The benefit of such an increase in radius is that the "cold set" or permanent deformation assumed by the tape 18 when in prolonged contact with the guides 24 and 26 is greatly reduced. This reduction in cold set reduces signal distortion which is a problem with tape guides having a small radius of curvature.

Although only a limited number of embodiments of the present invention have been described, it is recognized that modifications will be apparent to those skilled in the art. For example, the upper surfaces of the support 34 and the studs 46 could be rounded or beveled to facilitate assembly. All such modifications falling within the scope of the appended# claims are intended to be included in the present invention.

Claims

1. A tape guide for a tape cassette around which recording tape may be wrapped to change the direction of tape travel, comprising: an arcuate segment of a cylinder disposed perpendicular to the direction of tape travel, the arcuate segment including that arcuate portion of a cylinder which contacts the tape, the remaining arcuate portion of the cylinder being eliminated from the tape guide to reduce the area occupied within the tape cassette by the tape guide and thereby permit an increase in the radius of the tape guide without increasing substantially the occupied area; and means for attaching the tape guide to the tape cassette.

2. A tape guide as claimed in Claim 1 in which the tape guide is substantially at 1800 segment of a cylinder.

3. A tape guide as claimed in claim 1 in which the tape guide further includes flanges extending from the arcuate segment to contain the tape in contact with the tape guide.

4. A tape guide as claimed in Claim 1 substantially as herein described with reference to the accompanying drawings.